1. Technical Field
Aspects and embodiments disclosed herein relate generally to methods and apparatus for mounting porous hollow filtration membranes in a membrane filtration system.
2. Discussion of Related Art
Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.
Synthetic polymeric membranes are well known in the field of ultrafiltration and microfiltration for a variety of implementations, including desalination, gas separation, filtration, and dialysis. The properties of the membranes vary depending on the morphology of the membranes, for example, depending on parameters such as symmetry, pore shape, and pore size, and the chemical nature of the polymeric material used to form the membrane.
A large membrane surface area may be provided when a large filtrate flow is desired. In commercial embodiments, a large number of hollow porous membranes may be mounted together and housed in filtration modules. A commonly used technique to reduce the size of the filtration apparatus is to form the hollow porous membranes in the shape of hollow porous fibers. The hollow porous membranes act in parallel to filter a feed liquid, for example, water for purification. By producing a pressure differential across the membrane walls, the liquid is forced to flow through the pores of the walls of each of the hollow porous membranes while contaminants remain trapped on one side of the membranes and filtrate is withdrawn from the other side. In systems where feed liquid is applied to the outer walls of the membranes (outside-in filtration), the filtrate collects inside the hollow regions, cavities or channels (known as lumens) within the porous hollow membranes and is drawn off through ends of the lumens.
By sealing the ends of a porous hollow membrane in a module pot an impenetrable barrier may be formed between the feed and the filtrate. It is desirable that the seal formed by the barrier between the feed and filtrate be maintained to avoid contamination of the filtrate with feed. It is thus desirable that such module pots be designed to withstand forces such as hydraulic pressure from fluid flow inside the filtration module which might otherwise compromise the seal between the feed and the filtrate.
In addition to sealing the ends of porous hollow membranes, a module pot may be designed to perform further functions including structurally supporting and mounting the membranes within a module or otherwise within a filtration system. In some filtration arrangements, filtrate is withdrawn only from one end of the membranes and the other ends are merely sealed and supported by a potting head. In other arrangements, only one potting head is provided with the membranes being looped with both open ends located in the same potting head.
In some potting arrangements, the porous membrane ends may be sealingly potted using a curable resin material with the porous membrane ends being positioned within the resin material in its liquid non-cured state. The resin material may be allowed to cure to form a generally solid potting head. The curable resin material may be surrounded by a potting sleeve. The potting sleeve may be used to provide an interface between the potting head formed by the cured resin material and associated equipment such as headers and mounting apparatus.